The invention relates to a bed scale for the medical field, with which beds can be weighed.
Such bed scales have as a rule four measuring feet each of which can support one leg of the bed, in particular for example a bed roller of a movable bed, and is provided with a force transducer or sensor. The force transducer, for example a weighing cell, delivers a signal which represents the weight force acting on the measuring foot. The measuring feet have transmission devices for signal transmission to an evaluation device which receives and evaluates their signals. In many cases the evaluation device is designed as a reading and operating device which receives the signals of the measuring feet and is thus prepared to deliver a reading which depends on the weight force bearing on the measuring feet. The reading and operating device can be prepared for example such that the weight of the bed can be subtracted and then only the weight of the patient is displayed.
Such bed scales are known for example from DE 72 25 247 U1. The bed scale has four measuring feet each with a receiving means adapted to the outer shape of a bed roller. In order to employ and use the bed scale the bed is lifted and one measuring foot is placed under each bed roller and the bed is then lowered onto the measuring feet. For this purpose either the bed has to be lifted as a whole, which requires an expensive lifting device, or it has to be lifted firstly at one end and the measuring feet placed under the bed rollers at this end and then lifted at the opposite end and the measuring feet placed under the remaining bed rollers. With both alternatives the placing of the bed on the measuring feet of the bed scales is very laborious and time-consuming for the staff. The same difficulties result for beds without bed rollers, which likewise have to be lifted in order to be placed on the measuring feet.
With other bed scales the measuring feet are each provided with a ramp onto which the bed rollers can be pushed. Firstly the bed is pushed such that all four bed rollers are swivelled into a straight position suitable for pushing-on. The ramps of the measuring feet then have to be positioned at the bed rollers and then the bed is pushed over the ramps simultaneously onto the four measuring feet. Expenditure of a considerable force may be required to push the bed onto the measuring feet. Furthermore the measuring feet may slip during the pushing-on or one of the bed rollers swivel, which makes the repetition of the entire process necessary.
The known bed scales thus have the disadvantage that the placing of the legs of the bed onto the measuring feet is associated with considerable difficulties. Furthermore, the possible difficulties which may occur while placing the bed onto the measuring feet are such that, generally, it is not possible for a patient to be in it. Furthermore, if the measuring feet are not wholly precisely positioned, and they do not correspond wholly precisely to the position of the four legs or the bed rollers at the legs, lateral forces may act on the measuring feet when the bed is placed onto the measuring feet. Such lateral forces can affect the measurements of the force transducer and thus distort the results delivered by the bed scale.
It is the object of the present invention to produce bed scales which are easy to handle and measure precisely.
The characterizing features of patent claim 1 in conjunction with its preamble serve to achieve this object. Advantageous embodiments of the invention are stated in the dependent claims.
According to the present invention each measuring foot is designed as a kind of angle lever which can be moved along the floor on sliding elements, preferably rollers. A rocker is swivellably attached to the shorter lever arm and is adapted to be able to be pushed laterally onto a leg of the bed standing on the floor to engage it. The rocker can be designed for example such that it can be pushed laterally onto a bed roller of the leg to accomodate it for lifting while the bed roller is resting on the floor. In order to push the rocker onto the leg the angle lever arrangement is pushed forward on its sliding elements onto the leg until the rocker engages in form-locking manner at parts of the leg, in order to lift same. The rocker can for example be designed such that it can be pushed onto a bed roller at the bottom end of the leg standing on the floor, and that it, in its pushed-on state, encompasses parts of the lower hemisphere of the bed roller such that the latter can be lifted by the rocker. The suspension mounting of the rocker on the shorter lever arm and the longer activating lever of the angle lever arrangement and its sliding elements are arranged such that, when the activating lever is pressed down, the rocker is lifted by the shorter lever arm and its suspension mounting moved out over the dead centre, in which the suspension mounting of the rocker lies vertically above the sliding elements of the angle lever arrangement. In this way, the angle lever arrangement with lifted rocker reaches a stable position beyond the dead centre, in which the leg of the bed is supported by the rocker alone. In the stable end-position the angle lever arrangement rests on the floor with at least one further point beside the slide elements, such that a secure position of the measuring foot is achieved. A force transducer, for example a weighing cell, is provided in each measuring foot, which delivers a signal from which a measurement for the weight force acting on the rocker can be determined. The signals of the force transducer are transmitted to the evaluation device via transmission devices either with cables or without wires.
As the activating lever can be designed clearly longer than the shorter lever arm, the activation of the angle lever arrangement for lifting the bed rollers is possible for the staff with little expenditure of force.
Furthermore, incorrect positioning of the legs on the measuring feet cannot occur, as the rocker can be pushed laterally onto a leg of the bed while the leg is standing on the floor, to be able to grip this leg to lift it. Because the sliding elements of the measuring foot move under the leg of the bed during the lifting process, lateral forces cannot develop, as the measuring feet are movable in cross direction during the lifting process.
In principle the bed scales can be used for all types of beds, including simple beds which have their legs standing on the floor without bed rollers. Many beds in the medical field are provided with bed rollers on their legs such that they are movable. It is preferred for these beds that the measuring feet are designed such that they can accommodate the bed rollers. It is not necessary with the present bed scales that all bed rollers are firstly aligned in a uniform direction, as the measuring feet can also be pushed onto slanted or inclined bed rollers.
With the bed scales according to the invention the placing of the bed onto the measuring feet is made considerably easier and also requires no further lifting devices. The ease of handling and user-friendliness of the bed scales are considerably improved thereby.
The measuring feet can be placed in succession at the four bed rollers and lifted. The activation force for each lever process is small due to the length of the activating lever. The bed scales can therefore be installed by all nursing staff. Furthermore, when lifting the bed, it needs to be lifted only slightly such that the rocker comes away from the floor; with such a slight lifting a patient can also be in the bed during the lifting. Furthermore no moving of the bed is necessary with the scales according to the invention. In addition the bed rollers do not need to be set in a uniform direction beforehand, as each measuring foot can also be pushed onto a bed roller which is inclined and this can then be lifted.